Wilhelm,M.; Battista,H.J.; Obendorf,D.;

A versatile, sensitive, and selective high-performance liquid chromatographic (HPLC) procedure for the determination of common benzodiazepines and some of their most frequently occurring metabolites in forensic samples was developed and optimized with respect to effective and rapid sample preparation and high selectivity of the analytical assay. The optimized method includes liquid-liquid extraction of the drugs with chloroform followed by isocratic reversed- phase chromatography on a LiChrospher-100 RP-8ec column (150 x 4.6-mm i.d.) with a mobile phase consisting of 0.03 mol/L acetate buffer (pH 4.6)/acetonitrile (55:45, v/v). The use of dual-mode detection made up of UV-detection (250 nm) in series with reductive electrochemical detection (-1.4 V vs. Ag/AgCl) at the hanging mercury drop electrode permits the detection and quantitation of benzodiazepines even in degraded samples with higher selectivities than usually reached with conventional HPLC techniques. Depending on the actual benzodiazepine species, detection limits are in the range of 2.0 to 14.1 ng/mL. Mean recovery values of the drugs from blood range from 82 to 92%; within- day and day-to-day repeatabilities typically lie between 3 and 9%. Several case work examples demonstrate the high selectivity and remarkably low matrix sensitivity of the described assay

J Anal.Toxicol. 2001 25(4):250-257
PubMed: 11386638